Optical attenuators provide a variety of useful functions. One function of attenuators is to reduce the intensity of optical signals entering a photosensitive device to preclude device damage and/or overloading. In other applications, attenuators may serve as noise discriminators by reducing the intensity of spurious signals received by an optical device to a level below the device response threshold. In still other applications, attenuators are used to simulate the operation of optical systems without the need for long lengths of optical fibers.
Optical attenuators which provide fixed and variable amounts of attenuation are commercially available. Fixed attenuators, however, are oftentimes undesirable for attenuator applications as the commercially available attenuation values only approximate the precise attenuation required and/or many different valued fixed attenuators are required. On the other hand, while commercially available variable attenuators avoid the above problems, the range of attenuation may be insufficient for certain applications. Moreover, the apparatus is not readily available for use with either multimode or monomode fibers.